Laminated inductor

Abstract

The invention provides a laminated inductor which ensures insulation characteristics and reduces reduction of magnetic permeability. This laminated inductor is provided with a blank (10) having a magnetic body (M) in which a metal magnetic body layer (ML) containing metal magnetic body particles (MP) is laminated, a coil disposed inside the magnetic body (M) and around which coil conductors (CD) are wound, and an insulator (I) disposed between the coil conductors (CD) in the lamination direction. The insulator (I) has a contact part (I1) which extends in a direction intersecting the lamination direction and which contacts the coil conductor (CD), and protruding parts (I2) which are provided at both ends of the contact part (I1) in a direction orthogonal to the lamination direction and which extend toward the outside of both sides of the coil conductor (CD) in the direction orthogonal to the lamination direction, and the thickness of the protruding parts (I2) is smaller than the thickness of the contact part (I1).

Description

Technical Field

[0001] This disclosure relates to multilayer inductors. Background Technology

[0002] In patent document 1 (refer to claim 1 and...) Figure 3 A laminated coil assembly is disclosed in which the average particle size of the soft magnetic metal powder located inside the coil when viewed from the Z direction is larger than the average particle size of the soft magnetic metal powder located between each coil conductor that is adjacent to each other in the Z direction, thereby improving the permeability of the blank.

[0003] Additionally, in Patent Document 2 (refer to claim 3 and...) Figure 3 A coil component is disclosed in which the width dimension of multiple insulating portions orthogonal to a axial direction is greater than the width dimension of multiple winding portions orthogonal to a axial direction, thereby ensuring stable electrical insulation between the winding portions.

[0004] Patent document 1: Japanese Patent Application Publication No. 2018-6411.

[0005] Patent Document 2: Japanese Patent Application Publication No. 2017-228768.

[0006] The laminated coil assembly described in Patent Document 1 achieves insulation through a low-permeability section composed of soft magnetic metal powder located between the coil conductors. However, the width dimension of the low-permeability section in the X direction (refer to Patent Document 1) is limited. Figure 3 The width dimension in the X direction of the coil conductor is the same as that of the coil conductor, so there are concerns about the reliability of the insulation.

[0007] In contrast, Patent Document 2 (see Figure 3 The coil component described herein is configured such that the width dimension Ws of the insulator portion is larger than the width dimension Wc of the winding portion. However, due to the reduced magnetic flux flow caused by the insulator portion extending from the winding portion, the overall permeability of the coil component decreases. Summary of the Invention

[0008] This disclosure was made in view of the following problem: that is, this disclosure provides a multilayer inductor that further reduces the reduction in permeability while ensuring insulation properties.

[0009] The multilayer inductor disclosed herein comprises a blank having a magnetic body having a layer of metallic magnetic body containing metallic magnetic particles stacked thereon, a coil having a coil conductor wound inside the magnetic body, and an insulator disposed between the coil conductors in the stacking direction.

[0010] The above-mentioned insulator has the following characteristics:

[0011] The contact portion with the coil conductor extending in a direction intersecting the aforementioned stacking direction; and

[0012] The protrusions are located at both ends of the contact portion in a direction orthogonal to the stacking direction, and extend outwards towards both sides of the coil conductor in a direction orthogonal to the stacking direction.

[0013] The thickness of the protruding portion is thinner than the thickness of the contact portion.

[0014] According to this disclosure, a multilayer inductor can be provided that further reduces the decrease in permeability while ensuring insulation properties. Specifically, since the insulator disposed between the coil conductors in the stacking direction has a contact portion extending along a direction intersecting the stacking direction and a protrusion portion disposed at both ends in a direction orthogonal to the stacking direction and extending outward toward the sides of the coil conductors in the direction orthogonal to the stacking direction, insulation properties can be ensured. In addition, in the insulator disposed between the coil conductors in the stacking direction, the thickness of the protrusion portion extending outward from both sides of the coil conductor is thinner than the thickness of the contact portion in contact with the coil conductor, thus making it difficult for the decrease in magnetic flux flow caused by the insulator to occur, and further reducing the decrease in permeability. Attached Figure Description

[0015] Figure 1 This is a perspective view of the stacked inductor disclosed herein.

[0016] Figure 2 This is an exploded perspective view of the stacked inductor of the first embodiment.

[0017] Figure 3 yes Figure 2 A cross-sectional view in the direction of the arrow along line III-III.

[0018] Figure 4 yes Figure 3 Enlarged sectional view of the main part.

[0019] Figure 5 This is a cross-sectional view of a multilayer inductor in another embodiment.

[0020] Figure 6 This is a cross-sectional view of the stacked inductor according to the second embodiment.

[0021] Figure 7 yes Figure 6 Enlarged sectional view of the main part.

[0022] Figure 8 (A) to (G) are explanatory diagrams illustrating the manufacturing method of the multilayer inductor of this disclosure. Detailed Implementation

[0023] The multilayer inductor of this disclosure will now be described. Furthermore, this disclosure is not limited to the following structures, and appropriate modifications may be made without departing from the spirit of this disclosure. Additionally, structures combining multiple preferred structures described below are also included in this disclosure.

[0024] The multilayer inductors disclosed herein are used, for example, in DC-DC converters. Furthermore, the inductors disclosed herein can also be used for applications other than DC-DC converters.

[0025] In this specification, terms indicating relationships between elements (e.g., "parallel," "orthogonal," etc.) and terms indicating the shape of elements do not refer to a strict literal manner, but also to a practically equivalent range, such as a range containing a difference of about a few percent. Furthermore, in this specification, the orientation of the magnetic layers and coil conductors that are stacked to form the blank is defined as the "stack direction."

[0026] Furthermore, references to directions or orientations in this specification are for convenience only and are not intended to limit the scope of this disclosure unless explicitly stated otherwise. For example, relative terms such as "outer" (or outer side, exterior, or periphery) and "inner" (or inner side, interior, or periphery), and their derivatives, should be understood as referring to the direction as described or illustrated. In other words, unless explicitly stated otherwise, the invention is not limited to specific directions, orientations, or forms. Similarly, terms such as "set," "configured," and "connected," and their derivatives, are not limited to a direct manner unless explicitly stated otherwise, but can be used in a manner incorporating other elements such as inclusions.

[0027] The attached diagrams are schematic diagrams and may differ from the actual product in terms of dimensions, aspect ratio, etc.

[0028] <Inductor of the First Embodiment>

[0029] Reference Figures 1-5 The multilayer inductor of the first embodiment will be described. Figure 1 This is a perspective view of the stacked inductor disclosed herein. Figure 2 This is an exploded perspective view of the multilayer inductor according to the first embodiment. Figure 3 yes Figure 2 A cross-sectional view in the direction of the arrow on line III-III. Figure 4 yes Figure 3 Enlarged sectional view of the main part, Figure 5 This is a cross-sectional view of a multilayer inductor according to other embodiments. Furthermore, the shape and arrangement of the multilayer inductor and its constituent elements are not limited to the examples shown.

[0030] The multilayer inductor 1 of the first embodiment includes a blank 10, which has layers containing metallic magnetic particles MP (see reference). Figure 4 ) metallic magnetic layer ML (refer to) Figure 2 The magnetic body M, the coil C which is disposed inside the magnetic body M and has a coil conductor CD wound around it, and the insulator I disposed between the coil conductor CD in the stacking direction.

[0031] In this embodiment, the blank 10 includes a first coil C1 and a second coil C2 disposed on the upper side of the first coil C1 in the height direction T. The first coil C1 is stacked with the stacked groups G6 to G8 described later (refer to...). Figure 2 The first coil conductor CD1 between layers passes through the through-hole conductor V (see reference). Figure 3 The coils are connected in a spiral shape, thus winding them within the blank 10. The second coil C2 is stacked with the stacked groups G2~G4 described later (refer to...). Figure 2 The second coil conductor CD2 between layers is connected in a spiral shape via a through-hole conductor (not shown), thereby being wound inside the blank 10.

[0032] Furthermore, the coil inside the blank 10 is not limited to the above-described form; it can also be a form with one coil, or a form with two or more coils. For example, as... Figure 5 The diagram also shows a configuration where the blank 10 has four coils C1 to C4. Specifically, it can be... Figure 5 The blank 10 shown has a third coil C3 arranged relative to the first coil C1 in a direction orthogonal to the stacking direction, and a fourth coil C4 arranged relative to the second coil C2 in a direction orthogonal to the stacking direction.

[0033] The following is a detailed description of each component.

[0034] -Blank-

[0035] The blank 10 is, for example, a cuboid shape with six faces or a roughly cuboid shape. The blank 10 may also have chamfered corners and edges. The corners are the parts where three faces of the blank 10 intersect, and the edges are the parts where two faces of the blank 10 intersect.

[0036] exist Figure 1 In the diagram, the length, width, and height directions of the multilayer inductor 1 and the blank 10 are shown as the L direction, W direction, and T direction, respectively. The length direction L, width direction W, and height direction T are orthogonal to each other. The mounting surface of the multilayer inductor 1 is, for example, a surface parallel to the length direction L and the width direction W (LW surface).

[0037] Figure 1The billet 10 shown has a first main surface 11 and a second main surface 12 opposite each other in the height direction T, a first end surface 13 and a second end surface 14 orthogonal to the height direction T and opposite each other in the length direction L, and a first side surface 15 and a second side surface 16 opposite each other in the width direction W orthogonal to both the length direction L and the height direction T. Figure 1 In the example shown, the first main surface 11 of the billet 10 corresponds to the mounting surface (bottom surface) of the billet 10. In addition, the second main surface 12 can also be the mounting surface of the billet 10.

[0038] The blank 10 includes a magnetic body M, a coil C, and an insulator I. Furthermore, the blank 10 has a laminated structure in which multiple metallic magnetic body layers ML, forming the insulator I and the coil conductor CD, are stacked in the lamination direction (e.g., the height direction T), and multiple metallic magnetic body layers ML forming the insulator I are also stacked. In this embodiment, as... Figure 2 The structure shown is formed by stacking layers G1 to G10, which include at least one layer of metallic magnetic material ML and a coil conductor CD (or only the metallic magnetic material layer ML). Furthermore, the boundaries of each layer in the stacked structure of the blank 10 disappear. Additionally, each stacked layer can be formed by stacking multiple layers of the same pattern.

[0039] (Stacked group G1)

[0040] The laminate group G1 has a metallic magnetic layer ML, which constitutes the second main surface 12 of the blank 10.

[0041] (Stacked group G2)

[0042] The stacked assembly G2 has a metallic magnetic layer ML, an insulator (not shown) disposed on the metallic magnetic layer ML, and a second coil conductor CD2 formed on the insulator that constitutes part of the second coil C2.

[0043] The second coil conductor CD2 of the laminate G2 constitutes one turn of the second coil C2. More specifically, the second coil conductor CD2 is disposed on an insulator formed along the thickness direction of the metallic magnetic layer ML, approximately at the outer periphery of the metallic magnetic layer ML. One end of the second coil conductor CD2 is connected to a through-hole conductor (not shown) for connection with the second coil conductor CD2 disposed on the insulator of the metallic magnetic layer ML of the laminate G4, and the other end of the second coil conductor CD2 is connected to a fourth through-hole conductor (not shown) for electrical connection with the fourth external electrode E4.

[0044] (Stacked group G3)

[0045] The stacked assembly G3 has a metallic magnetic layer ML, an insulator I disposed in the metallic magnetic layer ML, a through-hole conductor V disposed in the insulator I, and a fourth through-hole conductor T4 disposed in the metallic magnetic layer ML.

[0046] The insulator I of the laminate group G3 is arranged in a shape corresponding to the winding shape of the second coil conductor CD2 of the laminate group G4 (described later). It is designed such that, in planar perspective, the planar area of ​​the insulator I of the laminate group G3 is larger than the planar area of ​​the second coil conductor CD2 of the laminate group G4. Therefore, in planar perspective, the insulator I of the laminate group G3 has an area overlapping with the second coil conductor CD2 and an area extending from the second coil conductor CD2. Furthermore, the area of ​​the insulator I extending from the second coil conductor CD2 (extended portion I2, as described later) is... Figure 3 or Figure 4 )) details.

[0047] The through-hole conductor V of the laminate group G3 is positioned to connect to one end of the second coil conductor CD2 of the laminate group G2.

[0048] The fourth through-hole conductor T4 of the stacked assembly G3 connects to the fourth through-hole conductors T4 of adjacent stacked assemblies G2 and G4 in the stacking direction and is electrically connected to the fourth external electrode E4. Therefore, the fourth through-hole conductor T4 is positioned on the fourth external electrode E4 in planar perspective.

[0049] (Stacked group G4)

[0050] The stacked assembly G4 has a metallic magnetic layer ML, an insulator (not shown) disposed on the metallic magnetic layer ML, a second coil conductor CD2 formed on the insulator that constitutes part of the second coil C2, and a fourth through-hole conductor T4 disposed on the metallic magnetic layer ML.

[0051] The second coil conductor CD2 of the laminate G4 constitutes the remaining turns of the second coil C2. More specifically, the second coil conductor CD2 is disposed on an insulator formed along the thickness direction of the metallic magnetic layer ML, approximately at the outer periphery of the metallic magnetic layer ML. One end of the second coil conductor CD2 is connected to the second coil conductor CD2 disposed on the insulator of the metallic magnetic layer ML in the laminate G2, and the other end of the second coil conductor CD2 is connected to a third through-hole conductor (not shown) for electrical connection with the third external electrode E3.

[0052] The fourth through-hole conductor T4 of the stacked assembly G4 connects to the fourth through-hole conductors T4 of adjacent stacked assemblies G3 and G5 in the stacking direction and is electrically connected to the fourth external electrode E4. Therefore, the fourth through-hole conductor T4 can also be disposed at the corner of the metallic magnetic layer ML located on the fourth external electrode E4.

[0053] (Stacked group G5)

[0054] The stacked assembly G5 includes a metallic magnetic layer ML, an insulator I disposed in the metallic magnetic layer ML, a third through-hole conductor T3 disposed in the metallic magnetic layer ML, and a fourth through-hole conductor T4.

[0055] The insulator I of the laminate group G5 is configured to correspond to the winding shape of the first coil conductor CD1 of the laminate group G6 (described later). It is designed such that, in planar perspective, the flat area of ​​the insulator I of the laminate group G5 is larger than the flat area of ​​the first coil conductor CD1 of the laminate group G6. Therefore, in planar perspective, the insulator I of the laminate group G5 has an area overlapping with the first coil conductor CD1 and an area extending from the first coil conductor CD1. Furthermore, the insulator I of the laminate group G5 electrically insulates the first coil C1 from the second coil C2.

[0056] The third through-hole conductor T3 of the stacked assembly G5 connects to the third through-hole conductors T3 of adjacent stacked assemblies G4 and G6 in the stacking direction and is electrically connected to the third external electrode E3. Therefore, the third through-hole conductor T3 is positioned on the third external electrode E3 in planar perspective.

[0057] The fourth through-hole conductor T4 of the stacked assembly G5 connects to the fourth through-hole conductors T4 of adjacent stacked assemblies G4 and G6 in the stacking direction and is electrically connected to the fourth external electrode E4. Therefore, the fourth through-hole conductor T4 is positioned on the fourth external electrode E4 in planar perspective.

[0058] (Stacked group G6)

[0059] The stacked assembly G6 has a metallic magnetic layer ML, an insulator (not shown) disposed on the metallic magnetic layer ML, a first coil conductor CD1 formed on the insulator that constitutes part of the first coil C1, a third through-hole conductor T3 disposed on the metallic magnetic layer ML, and a fourth through-hole conductor T4.

[0060] The first coil conductor CD1 of the laminate group G6 constitutes one turn of the first coil C1. More specifically, the first coil conductor CD1 is disposed on an insulator formed along the thickness direction of the metallic magnetic layer ML, approximately at the outer periphery of the metallic magnetic layer ML. One end of the first coil conductor CD1 is provided with a through-hole conductor (not shown) for connection with the first coil conductor CD1 disposed on the insulator of the metallic magnetic layer ML in the laminate group G7, and the other end of the first coil conductor CD1 is provided with a second through-hole conductor (not shown) for electrical connection with the second external electrode E2.

[0061] The third through-hole conductor T3 of the stacked assembly G6 connects to the third through-hole conductors T3 of adjacent stacked assemblies G5 and G7 in the stacking direction and is electrically connected to the third external electrode E3. Therefore, the third through-hole conductor T3 can also be disposed at the corner of the metallic magnetic layer ML located on the third external electrode E3.

[0062] The fourth through-hole conductor T4 of the stacked assembly G6 connects to the fourth through-hole conductors T4 of adjacent stacked assemblies G5 and G7 in the stacking direction and is electrically connected to the fourth external electrode E4. Therefore, the fourth through-hole conductor T4 can also be disposed at the corner of the metallic magnetic layer ML located on the fourth external electrode E4.

[0063] (Stacked group G7)

[0064] The stacked assembly G7 has a metallic magnetic layer ML, an insulator I disposed in the metallic magnetic layer ML, a through-hole conductor V disposed in the insulator I, a second through-hole conductor T2 disposed in the metallic magnetic layer ML, a third through-hole conductor T3 disposed in the metallic magnetic layer ML, and a fourth through-hole conductor T4.

[0065] The insulator I of the laminate group G7 is arranged in a shape corresponding to the winding shape of the first coil conductor CD1 of the laminate group G8, which will be described later. It is designed such that, in planar perspective, the planar area of ​​the insulator I of the laminate group G7 is larger than the planar area of ​​the first coil conductor CD1 of the laminate group G8. Therefore, in planar perspective, the insulator I of the laminate group G7 has an area overlapping with the first coil conductor CD1 and an area extending from the first coil conductor CD1.

[0066] The through-hole conductor V of the laminate group G7 is positioned to connect to one end of the first coil conductor CD1 of the laminate group G6.

[0067] The second through-hole conductor T2 of the stack group G7 connects to the second through-hole conductors T2 of adjacent stack groups G6 and G8 in the stacking direction and is electrically connected to the second external electrode E2. Therefore, the second through-hole conductor T2 is positioned on the second external electrode E2 in planar perspective.

[0068] The third through-hole conductor T3 of the stacked assembly G7 connects to the third through-hole conductors T3 of adjacent stacked assemblies G6 and G8 in the stacking direction and is electrically connected to the third external electrode E3. Therefore, the third through-hole conductor T3 is positioned on the third external electrode E3 in planar perspective.

[0069] The fourth through-hole conductor T4 of the stack group G7 connects to the fourth through-hole conductors T4 of adjacent stack groups G6 and G8 in the stacking direction and is electrically connected to the fourth external electrode E4. Therefore, the fourth through-hole conductor T4 is positioned on the fourth external electrode E4 in planar perspective.

[0070] (Stacked group G8)

[0071] The stacked assembly G8 includes a metallic magnetic layer ML, an insulator (not shown) disposed on the metallic magnetic layer ML, a first coil conductor CD1 formed on the insulator that constitutes part of the first coil C1, and a second through-hole conductor T2, a third through-hole conductor T3, and a fourth through-hole conductor T4 disposed on the metallic magnetic layer ML.

[0072] The first coil conductor CD1 of the laminate group G8 constitutes the other turns of the first coil C1. More specifically, the second coil conductor CD2 is disposed on an insulator formed along the thickness direction of the metallic magnetic layer ML, approximately at the outer periphery of the metallic magnetic layer ML. One end of the first coil conductor CD1 is connected to the first coil conductor CD1 disposed on the insulator of the metallic magnetic layer ML in the laminate group G6, and the other end of the first coil conductor CD1 is provided with a first through-hole conductor (not shown) for electrical connection with the first external electrode E1.

[0073] The second through-hole conductor T2 of the stacked group G8 connects to the second through-hole conductors T2 of adjacent stacked groups G7 and G9 in the stacking direction and is electrically connected to the second external electrode E2. Alternatively, the second through-hole conductor T2 can also be disposed at the corner of the metallic magnetic layer ML located on the second external electrode E2.

[0074] The third through-hole conductor T3 of the stacked assembly G8 connects to the third through-hole conductors T3 of adjacent stacked assemblies G7 and G9 in the stacking direction and is electrically connected to the third external electrode E3. Alternatively, the third through-hole conductor T3 can also be disposed at the corner of the metallic magnetic layer ML located on the third external electrode E3.

[0075] The fourth through-hole conductor T4 of the stacked assembly G8 connects to the fourth through-hole conductors T4 of adjacent stacked assemblies G7 and G9 in the stacking direction and is electrically connected to the fourth external electrode E4. Alternatively, the fourth through-hole conductor T4 can also be disposed at the corner of the metallic magnetic layer ML located on the fourth external electrode E4.

[0076] (Stacked group G9)

[0077] In the stacked assembly G9, a first through-hole conductor T1, a second through-hole conductor T2, a third through-hole conductor T3, and a fourth through-hole conductor T4 are provided at the corner of the metallic magnetic layer ML. The areas of the first through-hole conductor T1 to the fourth through-hole conductor T4 of the stacked assemblies G1 to G9 are approximately the same when viewed from the stacking direction.

[0078] (Stacked group G10)

[0079] The laminate G10 has first to fourth through-hole conductors T1 to T4 at the corners of the metallic magnetic layer ML, with a flat area larger than that of the first to fourth through-hole conductors of the laminate G9. The first to fourth through-hole conductors T1 to T4 are used as the base electrodes for the external electrodes E1 to E4. By making the flat area of ​​the first to fourth through-hole conductors of the laminate G10 larger than that of the first to fourth through-hole conductors of the laminate G9, the strength during installation can be improved.

[0080] The thickness of the first coil conductor CD1 and the second coil conductor CD2 in each stacked assembly can be the same. The first coil conductor CD1 and the second coil conductor CD2 can be made of metallic conductors such as Ag or Cu, as an example of their material. For example, the first coil conductor CD1 and the second coil conductor CD2 can be formed by printing a conductive paste onto the aforementioned metallic magnetic layer ML.

[0081] As an example of the material for the first through-hole conductor T1 to the fourth through-hole conductor T4 and the through-hole conductor, it can be a metallic conductor such as Ag or Cu. Furthermore, the materials for the first through-hole conductor T1 to the fourth through-hole conductor T4 and the through-hole conductor can be the same as the materials used for the first coil conductor CD1 and the second coil conductor CD2, or they can be different types of materials. The through-hole conductor and the through-hole conductor can be formed, for example, by forming a through-hole on the aforementioned metallic magnetic layer ML and printing a conductive paste within the through-hole, or by printing a conductive paste and then printing the metallic magnetic layer ML outside the conductive paste.

[0082] As described above, if the blank 10 has a stacked structure with stacked groups G1 to G10, the design of the stacked inductor 1 has greater freedom. For example, when manufacturing a stacked inductor 1 with a first external electrode E1, a second external electrode E2, a third external electrode E3, and a fourth external electrode E4 on the bottom surface (first main surface 11) of the blank 10, it is easy to lead out the first coil C1 and the second coil C2 to the bottom surface side. In addition, the stacked structure with the above-mentioned stacked groups G1 to G10 can also be formed by sequentially printing (e.g., screen printing, etc.) materials constituting the metallic magnetic layer ML, the insulator I, the coil conductor CD, and the through-hole conductor and the via conductor from the second main surface 12 side or from the first main surface 11 side of the blank 10. In this case, each of the lamination groups G1 to G10 can be printed repeatedly until the metal magnetic layer ML, the insulator I, the coil conductor, and the through-hole conductor and via conductor reach the desired thickness.

[0083] The metallic magnetic layer ML contains metallic magnetic particles MP made of magnetic material (see reference). Figure 4The magnetic particles (MP) contain Fe (iron). More specifically, they can be Fe particles or Fe alloy particles. Fe alloys can be Fe-Si alloys, Fe-Si-Cr (chromium) alloys, Fe-Si-Al (aluminum) alloys, Fe-Si-B (boron)-P (phosphorus)-Cu (copper)-C (carbon) alloys, Fe-Si-B-Nb (niobium)-Cu alloys, etc. Additionally, the magnetic particles (MP) may contain undesirable impurities such as Cr, Mn (manganese), Cu, Ni (nickel), P, S (sulfur), or Co (cobalt). Furthermore, the magnetic particles (MP) will be detailed in the manufacturing method description, and they can be contained in the magnetic paste. Therefore, the magnetic particles may also contain elements that are more easily oxidized than Fe (e.g., Cr, Al, Li (lithium), Zn (zinc)) added during the preparation of the magnetic paste. By including Si in the metallic magnetic particles MP, the oxidation of the Fe element contained in the metallic magnetic particles can be suppressed, thereby further improving the permeability of the multilayer inductor 1.

[0084] The surface of the metallic magnetic particles (MP) composed of the aforementioned metallic magnetic material can be covered by an insulating coating (not shown). In this specification, "insulation" refers to a volume resistivity of 1 MΩcm or higher. Covering the surface of the metallic magnetic particles (MP) with an insulating coating improves the insulation between the MP particles. Methods for forming the insulating coating on the surface of the metallic magnetic particles (MP) include sol-gel methods and mechanochemical methods. The material constituting the insulating coating can be an oxide of P, Si, etc. Alternatively, the insulating coating can also be an oxide film formed by oxidizing the surface of the metallic magnetic particles (MP). Preferably, the thickness of the insulating coating is 1 nm or more and 50 nm or less, more preferably 1 nm or more and 30 nm or less, and even more preferably 1 nm or more and 20 nm or less. For example, the thickness of the insulating coating covering the surface of the metallic magnetic particles can be measured based on the obtained SEM image obtained by grinding a sample of the inductor using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0085] Preferably, the average particle size of the metallic magnetic particles MP in the metallic magnetic layer ML is larger than 2 μm and less than 30 μm, more preferably larger than 2 μm and less than 20 μm, and even more preferably larger than 2 μm and less than 10 μm. The average particle size of the metallic magnetic particles MP in the metallic magnetic layer ML can be measured by the following steps. A sample of the inductor is cut to obtain a sample profile. Specifically, the sample profile is obtained by cutting through the center of the blank and orthogonal to the mounting surface and end face of the blank. For the obtained profile, an area (e.g., 130 μm × 100 μm) at multiple locations (e.g., five locations) is photographed using SEM, and the SEM images obtained are analyzed using image analysis software (e.g., image analysis software "Win R00F" (manufactured by Mitani Corporation)) to determine the circular diameter of the metallic magnetic particles. The average value of the obtained circular diameters is taken as the average particle size of the metallic magnetic particles. In addition, the average particle size mentioned in this specification may refer to the average particle size D50 (the cumulative percentage particle size on a volume basis of 50%).

[0086] During the formation of the blank 10, heat treatment is performed. In this case, the metallic magnetic particles MP contained in the blank 10 have an oxide film on their surface. This oxide film originates from the metallic magnetic particles MP and is formed through heat treatment. In the blank 10, adjacent metallic magnetic particles MP are bonded to each other via the oxide film.

[0087] like Figure 3 , 4 As shown, the blank 10 has an insulator I disposed between the coil conductors CD in the lamination direction. Specifically, as described above, insulators I can be disposed between lamination groups G2 to G7 (refer to...). Figure 2 An insulator I is provided. The insulator I has a contact portion I1 that extends in a direction intersecting the lamination direction and contacts the coil conductor CD, and an extension portion I2 that extends outward from both sides of the coil conductor CD in a direction intersecting the lamination direction.

[0088] In this specification, "contact area" refers to the region where the coil conductor CD contacts the insulator I. Specifically, as... Figure 3 , Figure 4 As shown, this refers to the region located inside the thinner areas at both ends of the coil conductor CD in the direction orthogonal to the stacking direction, and inside the outermost non-contact position P1 in the direction orthogonal to the stacking direction where the coil conductor CD does not contact the insulator I. Furthermore, the determination of whether the coil conductor CD is in contact with the insulator I is made at 1000x magnification during SEM observation, with both the coil conductor CD and the insulator I within the field of view.

[0089] Furthermore, the "protrusion" referred to in this specification is provided at both ends of the contact portion I1 in a direction orthogonal to the lamination direction. Specifically, it refers not only to the front ends protruding from both ends of the coil conductor in a direction orthogonal to the lamination direction, but also to... Figure 4 As shown, this refers to the region that includes the coil conductor CD and the insulator I not being in contact, and that extends outward from the outermost non-contact position P1 in a direction orthogonal to the stacking direction.

[0090] As a characteristic feature of the inductor of this embodiment, the thickness of the protrusion I2 is thinner (or smaller) than the thickness of the contact portion I1 over the entire area. The thickness of the protrusion I2 and the thickness of the contact portion I1 can be measured by the steps described below.

[0091] First, the inductor sample was held vertically upright, and its perimeter was secured with resin. This exposed the LT surface. Grinding was then performed using a grinder to approximately half the depth in the W direction of the sample, exposing a cross-section parallel to the LT surface. To remove burrs from the internal conductors caused by grinding, the ground surface was machined using an ion milling machine (IM4000 ion milling unit manufactured by Hitachi High Tech Co., Ltd.) after grinding. The cross-section was then photographed at 1000x magnification using a SEM (JES Co., Ltd. SEM unit, model JSM-7900F) with the coil conductor CD and insulator I within the field of view.

[0092] like Figure 4 As shown, the thickness of the contact portion I1 is calculated based on the average thickness of three points: the central portion O1 of the part of the insulator I that contacts the coil conductor CD, and the intermediate position O2 between the central portion O1 and the non-contact position P1.

[0093] like Figure 4 As shown, in addition to the thicknesses at three locations—the midpoint P2 between the non-contact position P1 and the front end PE of the protrusion I2, the midpoint P3 between the front end PE and the midpoint P2, and the midpoint P4 between the non-contact position P1 and the midpoint P2—the thickness of the protrusion I2 on the other side of the contact portion I1 is also measured at the same location, and the thickness of the protrusion I2 is calculated based on the average of the thicknesses at these six locations.

[0094] In this way, the present disclosure can use the average thickness of the contact portion I1 and the average thickness of the protrusion I2 as a judgment criterion. By making the thickness of the protrusion I2 thinner than the thickness of the contact portion I1, it is difficult for the reduction in magnetic flux flow caused by the protrusion I2 of the insulator I to occur, and the insulation between the coil conductors CD can be ensured by the insulator I. In addition, it is preferable that... Figure 3The cross-section of the insulator I and the coil conductor CD is more preferably 80% or more in line with the judgment criteria that the average thickness of the contact portion I1 and the average thickness of the protrusion portion I2 are satisfied.

[0095] More specifically, if the thickness of insulator I is determined, the thickness at both ends of insulator I in the direction orthogonal to the stacking direction is thinner than the thickness at the center of insulator I in the direction orthogonal to the stacking direction. If the thickness of insulator I is in the above relationship, it is difficult for the decrease in magnetic flux flow caused by the two ends of insulator I to occur, and the insulation between coil conductors CD can be ensured by insulator I.

[0096] As a preferred method for thinning the protrusion I2, a recess RC can be provided on the surface of the protrusion I2, and metallic magnetic particles MP can be disposed in the recess RC. Specifically, as Figure 4 As shown, metallic magnetic particles MP can enter the recess RC on the surface of the protrusion I2. Furthermore, the reason why the metallic magnetic particles MP enter the recess RC on the surface of the protrusion I2 will be explained in detail in the manufacturing method of the multilayer inductor 1 described later. By thinning the protrusion I2 in this way, it is difficult for a decrease in permeability caused by the protrusion I2 to occur.

[0097] The size of the recess RC is above the particle size of the metallic magnetic material. By making the size of the recess RC above the particle size of the metallic magnetic material, the metallic magnetic material particles MP can be properly inserted.

[0098] Insulator I can be a material with higher insulation properties and lower permeability than a magnetic material formed by stacking metallic magnetic layers ML. Because insulator I is such a material, insulation properties are ensured, and it is more difficult for a decrease in permeability to occur.

[0099] As a more specific characteristic of insulator I, insulator I can possess non-magnetic properties. In this specification, "non-magnetic properties" refers to a relative permeability of 1. Even with such a material, because the thickness of the protrusion I2 in insulator I is thinner than the thickness of the contact portion I1, it is more difficult for a decrease in permeability to occur.

[0100] The material of insulator I in this embodiment may include at least one selected from the group consisting of non-magnetic ferrite, alumina, glass, and zirconium oxide. By using such a material, the insulation between the coil conductors CD can be further improved.

[0101] A first coil C1 and a second coil C2 are disposed inside the blank 10. The first coil C1 and the second coil C2 can be magnetically coupled. For example, the coupling coefficient between the first coil C1 and the second coil C2 is between 0.1 and 0.8. In addition, either two coils containing only the first coil C1 and the second coil C2 can be disposed inside the blank 10, or three or more coils containing the first coil C1 and the second coil C2 can be disposed.

[0102] - First coil -

[0103] The first coil C1 is disposed inside the blank 10. The first coil C1 has a conductor V through a through hole (refer to...). Figure 3 Multiple first coil conductors CD1, first through-hole conductor T1, and second through-hole conductor T2 are interconnected.

[0104] Multiple first coil conductors CD1 are arranged in two stack groups (stack groups G6 and G8, as described above) as described above. Figure 2 Thus, the first coil C1 has 1.75 turns through a double-layer structure. Furthermore, the length of the through-hole conductor V connecting the multiple first coil conductors CD1 in the stacking direction can be shorter than the length of the first through-hole conductor T1, or shorter than the length of the second through-hole conductor T2.

[0105] The first through-hole conductor T1 electrically connects the end of the first coil conductor CD1, which is closest to the bottom surface (first main surface 11) of the blank 10, in the first coil C1 to the first external electrode E1. The first through-hole conductor T1 extends along the stacking direction of the metallic magnetic layers (e.g., the height direction T of the blank). The first through-hole conductor T1 may also have a stacked structure.

[0106] The second through-hole conductor T2 electrically connects the other end of the first coil C1 to the second external electrode E2. The second through-hole conductor T2 extends along the stacking direction of the metallic magnetic layers (e.g., the height direction T of the blank). The second through-hole conductor T2 may also have a stacked structure.

[0107] -Second coil-

[0108] The second coil C2 can be disposed inside the blank 10 and above the first coil C1 in the stacking direction. The second coil C2 can have multiple second coil conductors CD2, a third through-hole conductor T3, and a fourth through-hole conductor T4 interconnected through through-hole conductors (not shown).

[0109] Multiple second coil conductors CD2, as described above, can be arranged in two stack groups (stack groups G2, G4 (see reference)). Figure 2Thus, the second coil C2 can be made into 1.75 turns through a double-layer structure. Furthermore, the length of the through-hole conductors (not shown) connecting the multiple second coil conductors CD2 to each other in the stacking direction can be shorter than the length of the third through-hole conductor T3, or the length of the fourth through-hole conductor T4.

[0110] The third through-hole conductor T3 electrically connects the end of the second winding portion of the second coil C2, which is closest to the bottom surface (first main surface 11) of the blank 10, to the third external electrode E3. The third through-hole conductor T3 can extend along the stacking direction of the metal magnetic layers (e.g., the height direction T of the blank). The third through-hole conductor T3 can also have a stacked structure.

[0111] The fourth through-hole conductor T4 can connect the other end of the second coil C2 to the fourth external electrode E4. The fourth through-hole conductor T4 can extend along the stacking direction of the metallic magnetic layers (e.g., the height direction T of the blank). The fourth through-hole conductor T4 can also have a stacked structure.

[0112] As explained above, in the insulator I between the coil conductors CD arranged in the stacking direction, the thickness of the protrusion I2 extending outward from both sides of the coil conductor CD is thinner than the thickness of the contact portion I1 that contacts the coil conductor CD. Therefore, it is difficult for the decrease in magnetic flux flow caused by the insulator I to occur, and the decrease in permeability is reduced compared with the prior art.

[0113] As a preferred configuration of the multilayer inductor 1, the thickness D1 at both ends of the coil conductor CD of the first coil C1 or the second coil C2 in the direction intersecting the stacking direction is thinner than the thickness D2 at the center of the coil conductor CD in the direction intersecting the stacking direction (see reference). Figure 3 ).

[0114] Here, the thickness D2 of the central portion of the coil conductor CD can be calculated by averaging the thicknesses at three points: the central portion and any two points near the central portion. Additionally, the thicknesses D1 at both ends of the coil conductor CD can be calculated by averaging the thicknesses at three points: the front end of the coil conductor CD and any two points near that front end. Furthermore, "nearby" refers to the area within 10% of the length of the coil conductor CD in the direction intersecting the stacking direction from the central portion. The thickness of the coil conductor CD can also be measured based on SEM images.

[0115] If the thickness of the coil conductor CD is within the aforementioned range, magnetic flux can be properly generated through the coil conductor CD.

[0116] -External Electrode-

[0117] External electrodes are provided on the bottom surface of the blank 10. The external electrodes include a first external electrode E1, a second external electrode E2, a third external electrode E3, and a fourth external electrode E4. The first external electrode E1 and the second external electrode E2 are electrically connected to the first coil C1. Furthermore, the third external electrode E3 and the fourth external electrode E4 are electrically connected to the second coil C2. By providing external electrodes on the bottom surface (first main surface 11) of the blank 10, the multilayer inductor 1 can be properly mounted on a mounting substrate or the like.

[0118] As an example, the external electrode can be made of various materials such as Cu (copper) and Ni (nickel). Furthermore, the external electrode can be formed in a single layer or in a multilayer structure of two or more layers. The external electrode can be formed by any method, but as an example, it can be an electroplated electrode formed by electroplating (e.g., electroless electroplating).

[0119] <Layered Inductor of the Second Embodiment>

[0120] Reference Figures 6-7 A second embodiment of the multilayer inductor disclosed herein will be described. Figure 6 This is a cross-sectional view of the stacked inductor according to the second embodiment. Figure 7 yes Figure 6 The enlarged cross-sectional view of the main part. The second embodiment of the multilayer inductor differs from the first embodiment of the multilayer inductor, which uses a non-magnetic material as the insulator I, in that the insulator I uses metallic magnetic particles. Other structures have been described in the multilayer inductor 1 above, so the following description will focus on the differences from the multilayer inductor of the first embodiment.

[0121] In the multilayer inductor 1 of this embodiment, the insulator I contains metallic magnetic particles, and the average particle size of the metallic magnetic particles contained in the insulator I is smaller than the average particle size of the metallic magnetic particles contained in the magnetic body M.

[0122] Specifically, the magnetic material M contains metallic magnetic particles with an average particle size greater than 2 μm and less than 30 μm, as described above; more preferably, greater than 2 μm and less than 20 μm; and even more preferably, greater than 2 μm and less than 10 μm. On the other hand, the insulator I contains metallic magnetic particles with an average particle size of less than 2 μm. Furthermore, it is known that, generally speaking, a smaller average particle size of metallic magnetic particles results in a higher insulation resistance.

[0123] In this way, during the formation of the magnetic material M and the insulator I, by using metallic magnetic particles with a relatively large average particle size and those with a relatively small average particle size, the smaller average particle size particles can easily enter the larger average particle size particles. Therefore, by incorporating the insulator I into the magnetic material M constituting the blank 10, the thickness at both ends of the insulator I becomes thinner. This reduces the flow of magnetic flux at the ends of the insulator I and decreases the particle size of the metallic magnetic particles in the insulator I, thereby increasing the insulation resistance. As a result, even if the magnetic material M of the blank 10 is incorporated into the insulator I, the insulation of the coil conductor can be ensured.

[0124] Here, the boundary between metallic magnetic particles with a larger average particle size and metallic magnetic particles with a smaller average particle size can be measured by the steps described below.

[0125] First, the inductor sample was held vertically upright, and its perimeter was secured with resin. This exposed the LT surface. Grinding was then completed using a grinder to approximately half the depth in the W direction of the sample, exposing a cross-section parallel to the LT surface. To remove burrs from the internal conductors caused by grinding, the ground surface was machined using an ion milling machine (IM4000 ion milling unit manufactured by Hitachi High Tech Co., Ltd.) after grinding. The cross-section was then photographed at 1000x magnification using a SEM (JES Co., Ltd. SEM unit, model JSM-7900F) with the coil conductor CD and insulator I within the field of view.

[0126] The SEM image was imported into the image analysis software "Win R00F" (manufactured by Mitani Shoji Co., Ltd.), and the circular diameters of the metallic magnetic particles near the ends of the coil conductors in the direction orthogonal to the stacking direction were determined. This allowed the determination of the positional relationship between regions with larger and smaller particle sizes of the metallic magnetic powder. Then, as... Figure 7 As shown, the boundary BL between the regions with larger particle sizes of the metallic magnetic powder and the regions with smaller particle sizes of the metallic magnetic powder is drawn.

[0127] Then, the thickness of the protrusion I2 and the thickness of the contact I1 are measured using the method described above. In this embodiment, the thickness of the protrusion I2 of the multilayer inductor 1 is also thinner than the thickness of the contact I1. Therefore, it is difficult for the decrease in magnetic flux flow caused by the protrusion I2 of the insulator I to occur, and the insulation between the coil conductors CD can be ensured by the insulator I.

[0128] In the insulator I of this embodiment, the material of the metallic magnetic particles contained in the insulator I includes Fe. In other words, the insulator I differs from the first embodiment in that it is a magnetic material. Therefore, it is difficult to cause a decrease in magnetic flux flow, and the decrease in magnetic permeability can be further reduced compared to the first embodiment. Furthermore, the material of the metallic magnetic particles contained in the insulator I can be the same material as the magnetic material M, or it can be a different material.

[0129] <Manufacturing Method of Multilayer Inductors>

[0130] Next, refer to Figure 8 Methods for manufacturing the multilayer inductor disclosed herein are described in (A) to (G). The method for manufacturing the multilayer inductor disclosed herein may include a blank forming process.

[0131] - Billet Formation Process -

[0132] The blank forming process includes a stack forming process for forming a stack constituting the blank 10 and a firing process for firing the stack.

[0133] • Laminated body formation process

[0134] First, a metallic magnetic layer ML is prepared. The metallic magnetic layer ML is prepared by laminating a magnetic paste containing metallic magnetic particles MP with an average particle size preferably 1 μm or larger and 30 μm or smaller, more preferably 1 μm or larger and 20 μm or smaller, and even more preferably 1 μm or larger and 10 μm or smaller. Then, a conductive paste that serves as a coil conductor CD is printed onto the prepared metallic magnetic layer ML to form a laminate (see reference). Figure 8 (A)). As an example, forming Figure 2 The stacked group G8 is shown.

[0135] A magnetic paste containing the aforementioned metallic magnetic particles MP is coated onto the formed laminate (see reference). Figure 8 (B)). For the coating stack of the magnetic paste, the metal magnetic layer ML is printed to cover the width-direction end Ce of the upper surface of the coil conductor CD, and the central part Cc of the upper surface of the coil conductor is exposed.

[0136] Next, the insulator I is printed by the metallic magnetic layer ML that spans the central portion Cc across the width direction of the exposed upper surface of the coil conductor CD and the end Ce covering the upper surface of the coil conductor CD (see reference). Figure 8(C)). At this time, the insulator I is printed such that the central portion Ic of the upper surface of the coil conductor CD in the width direction is thicker, and the two end portions Ie of the upper surface of the upper surface of the coil conductor CD in the width direction are thinner. Furthermore, the upper surface of the central portion Ic of the upper surface of the upper surface of the coil conductor CD protrudes compared to the upper surface of the two end portions Ie of the upper surface of the upper surface of the coil conductor CD. Alternatively, the upper surface of the central portion Ic may be flat and not protruding compared to the upper surfaces of the two end portions Ie.

[0137] Next, a layered magnetic paste is coated around insulator I, forming an example. Figure 2 The portion of the laminate group G8 shown above, excluding the coil conductors of laminate groups G7 and G6 (see reference). Figure 8 (D)). Further, a conductive paste, which becomes the coil conductor CD, is printed onto the formed laminate (see reference). Figure 8 (E)), and a magnetic paste forming a metallic magnetic layer ML is printed around the conductive paste (see reference). Figure 8 (F)). Repeat these steps to make Figure 2 The stacked groups are shown in the diagram.

[0138] After stacking the layers, compress the stacked groups in the stacking direction (see reference). Figure 8 (G)). Through this compression, the insulator I is compressed, the spacing between the coil conductors CD narrows, and the insulator I enters the laminate of the magnetic body M. As a result, in the laminated inductor 1 of this disclosure, the thickness of the aforementioned protrusion I2 can be made thinner than the thickness of the contact portion I1, making it difficult for the decrease in magnetic flux flow caused by the protrusion I2 of the insulator I to occur, and the insulation between the coil conductors CD can be ensured by the insulator I.

[0139] • Heat treatment process

[0140] After degreasing to remove the adhesive contained in the magnetic paste and conductive paste, the formed laminate is heat-treated. Through heat treatment, an oxide film is formed, and the metallic magnetic particles are bonded via the oxide film. The heat treatment temperature can be, for example, around 700°C. Furthermore, to improve the strength of the laminate, it can be impregnated with resin and cured. Epoxy resin is used as the resin impregnated with the laminate, but one or more resins selected from the group consisting of phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin can also be used. Through the above processes, a blank of the laminated inductor of this disclosure is formed.

[0141] After forming the blank 10 through the above-described process, external electrodes E1 to E4 are formed on the mounting surface (first main surface 11) of the blank 10 by a known electrode forming method, thereby manufacturing the multilayer inductor 1 of this disclosure.

[0142] Furthermore, the embodiments disclosed herein are illustrative of all points and are not intended to be limiting. For example, as a method to make the thickness of the protruding portion of the insulator thinner than the thickness of the contact portion, it is also possible to reduce the amount of non-magnetic material in the insulator paste by making the resin component in the insulator paste more abundant than the resin component in a magnetic paste containing metallic magnetic particles during the formation of the insulator. Figure 4 The method involves adjusting the content of the metallic magnetic powder. When this method is used, the insulator is compressed in the compression direction during the stacking process, and the magnetic powder of the stack enters the protruding portions at both ends of the insulator. During degreasing in the heat treatment process, the magnetic powder further enters the protruding portions at both ends of the insulator, thus further thinning the thickness at both ends of the insulator. Furthermore, the insulator I between the first coil C1 and the second coil C2 can also be a structure formed along the entire circumference of the coil in the winding direction, with the same area as the metallic magnetic powder layer. Although the insulator I between the first coil C1 and the second coil C2 can be omitted, its presence increases the withstand voltage between the coils and adjusts the coupling between them.

[0143] Furthermore, the scope of this invention is not limited to the embodiments described above, but is defined based on the claims. Additionally, the scope of this invention includes all modifications that are equivalent to and within the scope of the claims.

[0144] The inductors disclosed herein include the following methods.

[0145] <1> A multilayer inductor includes a blank having a magnetic body having a layer of metallic magnetic body containing metallic magnetic particles stacked on top of it, a coil having a coil conductor wound inside the magnetic body, and an insulator disposed between the coil conductors in the stacking direction.

[0146] The above-mentioned insulator has the following characteristics:

[0147] A contact portion extending in a direction intersecting the aforementioned stacking direction and contacting the aforementioned coil conductor; and

[0148] The protrusions are located at both ends of the contact portion in a direction orthogonal to the stacking direction, and extend outward toward the sides of the coil conductor in the direction orthogonal to the stacking direction.

[0149] The thickness of the protruding portion is thinner than the thickness of the contact portion.

[0150] <2> According to the stacked inductor described in <1>, a recess is provided on the surface of the protrusion, and the aforementioned metallic magnetic particles are disposed in the recess.

[0151] <3> According to <1> or <2>, the material of the metallic magnetic particles contained in the magnetic body includes Fe and Si.

[0152] <4> According to any one of <1> to <3>, the insulator described above is a material with higher insulation and lower permeability compared to the magnetic material described above.

[0153] <5> According to any one of <1> to <4>, the above-mentioned insulator is non-magnetic.

[0154] <6> According to <5> the multilayer inductor, the material of the non-magnetic metallic magnetic particles contained in the insulator includes at least one selected from the group consisting of non-magnetic ferrite, alumina, glass and zirconium oxide.

[0155] <7> According to any one of <1> to <6>, the insulator described above contains metallic magnetic particles.

[0156] The average particle size of the metallic magnetic particles contained in the insulator is smaller than the average particle size of the metallic magnetic particles contained in the magnetic material.

[0157] <8> According to the multilayer inductor described in <7>, the metallic magnetic particles contained in the above-mentioned insulator are metallic magnetic powder containing Fe or metallic magnetic powder containing Fe and Si.

[0158] <9> According to any one of <1> to <8>, the thickness of the two ends of the insulator in the direction intersecting the stacking direction is thinner than the thickness of the central part of the insulator in the direction intersecting the stacking direction.

[0159] <10> According to any one of <1> to <9>, the thickness of the two ends of the coil conductor in the direction orthogonal to the stacking direction is thinner than the thickness of the central portion of the coil conductor in the direction orthogonal to the stacking direction.

[0160] This disclosure can be used in multilayer inductors that further reduce the reduction in permeability while ensuring insulation properties.

[0161] Explanation of reference numerals in the attached figures

[0162] 1…Laminated inductor, 10…Bulkhead, 11…First main surface, 12…Second main surface, 13…First end face, 14…Second end face, 15…First side face, 16…Second side face, C…Coil, C1…First coil, C2…Second coil, C3…Third coil, C4…Fourth coil, CD…Coil conductor, CD1…First coil conductor, CD2…Second coil conductor, E1…First external electrode, E2…Second external electrode, E3…Third external electrode, E4…Fourth external electrode G1~G10…Layer stack, I…Insulator, I1…Contact, I2…Extension, M…Magnetic material, MP…Metallic magnetic material particle, ML…Metallic magnetic material layer, RC…Recess, T1…First through-hole conductor, T2…Second through-hole conductor, T3…Third through-hole conductor, T4…Fourth through-hole conductor, V…Through-hole conductor, D1…Thickness at both ends of the coil conductor, D2…Thickness at both ends of the coil conductor, Cc…Central part of the coil, Ce…End of the coil, BL…Boundary.

Claims

1. A laminated inductor, wherein a green body having a magnetic body in which a metal magnetic body layer containing metal magnetic body particles is laminated, a coil in which a coil conductor is wound is disposed inside the magnetic body, and an insulator is disposed between the coil conductors in the lamination direction, the insulator has: a contact portion that contacts the coil conductor along a direction intersecting the lamination direction; and a protruding portion that is provided at both ends of the contact portion in a direction orthogonal to the lamination direction and extends toward the outside of both sides of the coil conductor in a direction orthogonal to the lamination direction, the thickness of the protruding portion is thinner than the thickness of the contact portion.

2. The laminated inductor according to claim 1, wherein a recessed portion is provided on the surface of the protruding portion, and the metal magnetic body particles are disposed in the recessed portion.

3. The laminated inductor according to claim 1 or 2, wherein the material of the metal magnetic body particles contained in the magnetic body includes Fe and Si.

4. The laminated inductor according to any one of claims 1 to 3, wherein the insulator is a material that has high insulation and low permeability compared to the magnetic body.

5. The laminated inductor according to any one of claims 1 to 4, wherein the insulator has non-magnetic properties.

6. The laminated inductor according to claim 5, wherein the material of the non-magnetic metal magnetic body particles contained in the insulator includes at least one selected from the group consisting of non-magnetic ferrite, alumina, glass, and zirconia.

7. The laminated inductor according to any one of claims 1 to 6, wherein the insulator contains metal magnetic body particles, the average particle diameter of the metal magnetic body particles contained in the insulator is smaller than the average particle diameter of the metal magnetic body particles contained in the magnetic body.

8. The laminated inductor according to claim 7, wherein the metal magnetic body particles contained in the insulator are metal magnetic powder containing Fe or metal magnetic powder containing Fe and Si.

9. The laminated inductor according to any one of claims 1 to 8, wherein the thickness of both end portions of the insulator in a direction orthogonal to the lamination direction is thinner than the thickness of a central portion of the insulator in a direction orthogonal to the lamination direction.

10. The laminated inductor according to any one of claims 1 to 9, wherein the thickness of both end portions of the coil conductor in a direction orthogonal to the lamination direction is thinner than the thickness of a central portion of the coil conductor in a direction orthogonal to the lamination direction.

Images